FILE – In this March 2, 2021, file photo, socially distanced, and with protective partitions, students work on an art project during class at the Sinaloa Middle School in Novato, Calif. U.S. guidelines that say students should be kept 6 feet apart in schools are receiving new scrutiny from federal health experts, state governments and education officials working to return as many children as possible to the classroom. (AP Photo/Haven Daley, File)